I have a small block chevy 383 stroker. It has a holley 670 street avenger carb, electric choke. Carb has been rebuilt, complete tune up not too long ago, new distributor. Runs good when warm and start right up when weather is warm. On cold (below 40) days, pump gas twice, hit the key, it starts, then stalls. I have to do this about 8 times before it stays running. Any suggestions?